The present invention relates to an ink jet head for use in an ink jet printer and capable of ejecting ink of particular color for forming a color image in combination with other ink jet heads, and more particularly to a structure and a method for mounting an ink jet head. Also, the present invention is concerned with a method and an apparatus for producing an ink jet head assembly.
Today, an ink jet printer capable of forming an image by ejecting ink drops via ejection ports is extensively used because of its low noise, small size configuration. An ink jet printer may be loaded with four ink jet heads each being filled with with one of cyan ink, magenta ink, yellow ink and black ink in order to form a full-color image. Specifically, to form a color image, the ink jet heads are arranged on the printer in an array, and each ejects ink of particular color toward a preselected position of a paper or similar recording medium. The prerequisite with this type of printer is that the four heads be accurately mounted to the printer in order to insure high image quality. If any one of the ink jet heads is deviated from a preselected position in each direction, then the ink drop ejected from the head cannot hit a desired position on a paper. This results in color misregister or the deviation of an image with respect to the contour of the paper and thereby deteriorates image quality.
To protect image quality from deterioration ascribable to the positional deviation of the heads, it is necessary that the relative position between the four heads themselves and the relative position between the heads and the paper be fixed with a deviation smaller than a preselected one.
While screws are predominant as means for fixing the heads 1a-1d in place, they bring about positional deviation as great as several ten microns to several hundred microns and fail to implement the required accuracy. Although the required accuracy may be available with screws, screws lower the yield and thereby increase the production cost. For this reason, adhesives expected to reduce the deviation, compared to screws, are being tested, as stated earlier. Specifically, adhesive is filled in a gap formed between two objects for positional adjustment (sometimes referred to as fill adhesion). The gap is greater than an adjustment margin. This kind of approach is taught in, e.g., Japanese Patent Laid-Open Publication No. 7-89185. Specifically, a gap between desired objects is selected such that the objects do not contact each other despite the accuracy of their configurations, and adhesive is filled in such a gap. It has also been proposed to mount an ink jet head to a head holder by using ultraviolet (UV) ray curable adhesive.
However, the conventional fill adhesion schemes are likely to fail to maintain the required positional accuracy of the ink jet head. This reduces the yield and causes the objects with low accuracy to be simply discarded, resulting in an increase in production cost. In addition, when the adhesive peels off after the production, the force fixing the head in place decreases and causes the printer to lose its fundamental function.